Ultrasonic Time Of Flight Research Articles

Reliability of Domestic Gas Flow Sensors with Hydrogen Admixtures.

Static flow sensors (e.g., thermal gas micro electro-mechanical sensors-MEMS-and ultrasonic time of flight) are becoming the prevailing technology for domestic gas metering and billing since they show advantages in respect to the traditional volumetric ones. However, they are expected to be influenced in-service by changes in gas composition, which in the future could be more frequent due to the spread of hydrogen admixtures in gas networks. In this paper, the authors present the results of an experimental campaign aimed at analyzing the in-service reliability of both static and volumetric gas meters with different hydrogen admixtures. The results show that the accuracy of volumetric and ultrasonic meters is always within the admitted limits for subsequent verification and even within those narrower of the initial verification. On the other hand, the accuracy of the first generation of thermal mass gas flow sensors is within the limits of the verification only when the hydrogen admixture is below 2%vol. At higher hydrogen content, in fact, the absolute weighted mean error ranges between 3.5% (with 5%vol of hydrogen) and 15.8% (with 10%vol of hydrogen).

A comparison of ultrasonic temperature monitoring using machine learning and physics-based methods for high-cycle thermal fatigue monitoring

Failure of pipe network components in so-called mixing zones due to high-cycle thermal fatigue (HCTF) can occur within nuclear power plants where fluids of different thermal and hydraulic properties interact. Given that the consequences of such failures are potentially deadly, a method to monitor HCTF non-invasively in real-time is expected to be of great use. This method may be realised by a technique to determine the inaccessible temperature distribution of a component since thermal gradients drive HCTF. Previous work showed that a physics-based method called the inverse thermal modelling (ITM) method can obtain the temperature distribution from external temperature and ultrasonic time of flight (TOF) measurements. This study investigated whether the long-short-term memory (LSTM) machine learning architecture could be a faster alternative to the ITM method for data inversion. On experimental data, a 25-member ensemble of LSTM networks achieved an ensemble median root mean square error (RMSE) of 1.04°C and an ensemble median mean error of 0.194°C (both relative to a resistance temperature device measurement). These values are similar to the ITM method which achieved a RMSE of 1.04°C and a mean error of 0.196°C. The single LSTM network and the ITM method achieved a computation-to-real-world time ratio of 0.008% and 14%, respectively demonstrating that both methods can invert data in real-time. Simulation studies revealed that LSTM performance is sensitive to small differences between the training and real-world parameters leading to unacceptable errors. However, these errors can be detected via an ensemble of independent networks and, corrected by simply adding a correction factor to the TOF prior to being input into the networks. The results show that LSTM has the potential to be an alternative to the ITM method; however, the authors favour ITM for temperature distribution monitoring given its interpretability.

Decoupling of the anode and cathode ultrasonic responses to the state of charge of a lithium-ion battery.

An ultrasonic method for lithium-ion battery (LIB) state of charge (SoC) estimation is a promising emerging technology which may largely improve the SoC estimation accuracy. Previously, it was unknown whether the SoC change induced ultrasonic signal change originated from the anode or the cathode, because the thicknesses of cathodes, anodes and separators are much smaller than the ultrasonic wavelength, which makes it impossible to decouple the anodic and cathodic influence. To quantitatively solve the above problem, we have designed a special half-cell architecture with an extra-thick separator (675 μm) to study the reflected ultrasonic signal. The thickened separator would significantly delay the reflection of ultrasonic waves from the counter-electrode (Li), so that the influence of the working electrode (LiFePO4 or graphite) on the ultrasonic wave can be studied separately. As a result, in the Gr anode, the time of flight (ToF) of the ultrasonic wave decreases with SoC, the changing rate coefficient of which is in the range of -110 to -70 ps μmGr thickness-1, depending on the compact density. A lower compact density electrode leads to a more significant ultrasonic ToF decrease and intensity increase while in the LFP cathode, the ToF increases with SoC, the changing rate coefficient of which is in the range of 15-43 ps μmLFP thickness-1. The ToF change of the transmitted ultrasound through multilayered LIB matches very well with the sum of the ToF change in each electrode measured with our half-cells.

Estimation of the ultrasonic time-of-flight for evaluating the axial force acting on bolt/nut assemblies under various mechanical and thermal conditions

The ultrasonic testing method is a prospective technique adopted for measuring the axial force acting on a bolt; the method is a nondestructive testing method employed for structural health monitoring. In ultrasonic testing, the ultrasonic time of flight (ToF) is obtained, and the axial force is computed using the mathematical relationship between the ultrasonic ToF and the axial force acting on the bolt. Therefore, it is essential to accurately compute the axial force from the ToF. However, existing theoretical equations do not reflect actual scenarios that bolt/nut assemblies may encounter under varying mechanical and thermal conditions. Therefore, the practical application of this method in engineering practices is limited. Establishing a mathematical relationship by considering mechanical and thermal deformation could serve as a fundamental solution for providing more accurate axial force measurement results in ultrasonic testing. In this study, we proposed calibration equations that could be applied to various types of bolts, which are primarily used in mechanical components. The calibration coefficients obtained from the experiments were substituted into the theoretical equations to improve the estimation accuracy of the ultrasonic ToF. Additionally, we compared the experimental results acquired using various types of bolts: M8, M10, M12, and M14, with the results obtained from the theoretical equations using the calibration coefficients. It was verified that it could make the axial force measurement of the bolt accurate as a calibration of the change of the ToF by the bolt deformation from the mechanically stressed region and the thermal conditions with 8.8% error. We expect that the theoretically and experimentally verified calibration equations can improve the reliability and robustness of mechanical components.

Potential of ultrasonic time-of-flight and amplitude as the measurement for state of charge and physical changings of lithium-ion batteries

Lithium-ion battery is an electrochemical energy storage device with high reliability safety and efficiency requirements, it is necessary to obtain and evaluate the battery performance in time. In this study, ultrasound is applied as a timely measuring method for the state-of-charge (SoC) of lithium-ion battery. In experimental presentation, the ultrasonic measurement is performed on commercial pouch cell, to identify the relationship between its SoC and the ultrasonic signals. The ultrasonic time-of-flight (ToF) and amplitude are sensitive to changes in physical properties of cell's layers during charging and discharging. Analyses of ultrasonic ToF signals present that sound velocity is influenced by the cell's temperature, the charging/discharging current and voltage, as well as the changing in layered materials. Analysis of ultrasonic amplitude shows that amplitude is properly correlated with physical (volume) changing in anode and cathode layers, as a function of the SoC. This ultrasonic amplitude measurement shows the potential application as one real-time diagnostic technique for lithium-ion battery.

Ультразвуковой метод определения ориентации углеродных нанотрубок при использовании разреженного представления

Carbon nanotubes orientation has a significant impact on the performance of carbon nanotubes/epoxy resin (CNTs/EP) composite materials. The ultrasonic velocity is sensitive to the degree of carbon nanotubes orientation. However, the time-of-flight (TOF) is difficulty to accurately measured due to ultrasonic echo aliasing and waveform distortion occurred in the thin CNTs/EP composite material. Therefore, the ultrasonic characterization method of carbon nanotubes orientation based on the sparse representation is studied in this paper. Two groups of CNTs/EP specimens are taken as research objects. Firstly, the dictionary is constructed by Gabor function，and the matching degree between dictionary and ultrasonic echo signals is researched. Then, the matching pursuit (MP) algorithm is used to solve the problem of dictionary redundancy and obtain the best matching atom; the signal reconstruction is completed and ultrasonic TOF of carbon nanotubes is extracted more accurately. Finally, a carbon nanotubes orientation prediction model based on the sparse representation is established. The result shows that the Gabor dictionary has good similarity with ultrasonic echo signals and the root mean square relative error is 0.0147. The degree of carbon nanotubes orientation and ultrasonic velocity have positive correlation. The carbon nanotubes orientation prediction model relative error is 5.58%. This paper has provided an effective method to characterize the degree of carbon nanotubes orientation.

Low-cost Solutions for Velocimetry in Rotating and Opaque Fluid Experiments using Ultrasonic Time of Flight

Many common techniques for flow measurement, such as Particle Image Velocimetry (PIV) or Ultrasonic Doppler Velocimetry (UDV), rely on the presence of reflectors in the fluid. These methods fail to operate when e.g centrifugal or gravitational acceleration leads to a rarefaction of scatterers in the fluid, as for instance in rapidly rotating experiments. In this article we present two low-cost implementations for flow measurement based on the transit time (or Time of Flight) of acoustic waves, that do not require the presence of scatterers in the fluid. We compare our two implementations against UDV in a well controlled experiment with a simple oscillating flow and show we can achieve measurements in the sub-centimeter per second velocity range with an accuracy of sim 5-10%. We also perform measurements in a rotating experiment with a complex flow structure from which we extract the mean zonal flow, which is in good agreement with theoretical predictions.

A Novel Ultrasonic TOF Ranging System Using AlN Based PMUTs.

This paper presents a high-accuracy complementary metal oxide semiconductor (CMOS) driven ultrasonic ranging system based on air coupled aluminum nitride (AlN) based piezoelectric micromachined ultrasonic transducers (PMUTs) using time of flight (TOF). The mode shape and the time-frequency characteristics of PMUTs are simulated and analyzed. Two pieces of PMUTs with a frequency of 97 kHz and 96 kHz are applied. One is used to transmit and the other is used to receive ultrasonic waves. The Time to Digital Converter circuit (TDC), correlating the clock frequency with sound velocity, is utilized for range finding via TOF calculated from the system clock cycle. An application specific integrated circuit (ASIC) chip is designed and fabricated on a 0.18 μm CMOS process to acquire data from the PMUT. Compared to state of the art, the developed ranging system features a wide range and high accuracy, which allows to measure the range of 50 cm with an average error of 0.63 mm. AlN based PMUT is a promising candidate for an integrated portable ranging system.

Ultrasonic monitoring performance degradation of lithium ion battery

To monitor the performance and reliability of a lithium-ion battery during charge/discharge cycles, an ultrasonic time-of-flight (ToF) and attenuation measurement was performed. Ultrasonic ToF of the reflected pulse echo increased with the decrease in the state of charge (SoC) and with the increase in number of cycles (i.e., degradation). A health evaluation map relating SoC with ToF at various cycles was constructed. In this map, ultrasonic hysteresis was reported, of which area reflected the magnitude of irreversible electrochemical damage to the battery material. A linear correlation between the ToF and the number of cycles was observed.

Multi-strategy Measurement of High-resolution Ultrasonic TOF

Jiao, Y.; Li, Z.; Zhu, J., and Zhang, B., 2020. Multi-strategy measurement of high-resolution ultrasonic TOF. In: Zheng, C.W.; Wang, Q.; Zhan, C., and Yang, S.B. (eds.), Air-Sea Interaction and Coastal Environments of the Maritime and Polar Silk Roads. Journal of Coastal Research, Special Issue No. 99, pp. 389–395. Coconut Creek (Florida), ISSN 0749-0208.Ultrasonic transducers are widely used in liquid sound velocity measurement. Acquisition of time-of-flight (TOF) is the key technology of high precision measurement of sound velocity.In this paper, to measure TOF with high precision, a Multi-strategy Measurement technique is proposed, which is able to locate the region of interest of the signals received echo waveform, and the wavelet denoising is carried out. To evaluate the proposed method, in an identified environment, the experiments were performed under defined the distance between transmitter and receiver in pure water at 30°C. The experiments were performed that, in the sound velocity measurement, the method has a high adaptability, which can achieve the goal of removing noise and improving detection accuracy. Although this paper focus on sound velocity in pure water, the method described may also find application in air.

Ultrasonic online monitoring of the ham salting process. Methods for signal analysis: Time of flight calculation

In the dry-cured ham industry, an accurate control of the dry-salting process is especially complex because of the great heterogeneity of the meat pieces and the effect of different operational variables. The main objective of this study was to evaluate the feasibility of using an ultrasound system and methodology, adapted to the industry requirements, for the online monitoring of the ham dry-salting process. For that purpose, hams were dry salted for different times (4, 10, 11, 14, 16 and 30 days) at 2 °C. The cushion zone of the ham was placed over the transducers during salting and ultrasonic signals were taken automatically (5 min interval by using pulse-echo mode. Several methods of signal analysis were considered in order to assess the time of flight (TOF). TOF estimations by means of the energy threshold and cross-correlation methods (between the initial ultrasonic signal and the remaining signals measured during salting and between consecutive signals 5 min apart without interpolation) were affected by the low signal-to-noise ratio and the pulse distortion and were discarded for the online monitoring of ham salting. Otherwise, the cross-correlation method between consecutive signals (5 min apart) with interpolation n = 3 (CCM-CS n = 3), between non-consecutive signals (1 h apart) (CCM-NCS) and the phase spectrum method (PSM), provided close estimations of the variation of the TOF, which correlated well with the ham salt gain (R2 = 0.83 for CCM-CS n = 3, 0.93 for CCM-NCS and 0.90 for PSM). Consequently, the use of ultrasonic pulse-echo TOF measurements could be considered as a simple, non-invasive, non-destructive and reliable technique for the industrial monitoring of the ham dry-salting process.

Oxygen vacancy ordering and viscoelastic mechanical properties of doped ceria ceramics

Young's, shear and bulk moduli of Ce1-xSmxO2-x/2 (x ≤ 0.55) were studied using ultrasonic time of flight and nanoindentation techniques. Sound velocity measurements, corrected for sample porosity, demonstrate decrease in the unrelaxed ceramic moduli with increasing Sm-content. Room temperature creep under indenter load-hold, as well as time-dependent material stiffness, reveal a transition from prominent anelasticity in the fluorite phase to prominent elasticity in the double fluorite phase. This supports rearrangement of elastic dipoles under anisotropic stress, which occurs more readily when oxygen vacancies are not ordered on the crystal lattice, as the source of ceria anelastic behavior.

Research on parameter estimation in ultrasonic measurement of internal transient temperature distributions

A new reconstruction method of internal unsteady temperature distributions in solid structure using ultrasonic thermometry technique is presented in this paper. This method mainly consists of a joint of heat condution caculation and an inverse analysis for boundary parameter estimation using ultrasonic time of flight by Conjugate Gradient method. The principle for internal temperature sensing is based on temperature dependence of the velocity of the ultrasonic wave that propagates through solid material. Simulation and stability analysis are made in which classic function form of heat flux is estimated to illustrate accuracy, as well as factors of influencing quality of this reconstruction method. Validation experiments with a steel plate whose single side is heated by a heater and then cooled down by water are refered. It is verified that the temperature gradient and its variation estimated by this method agree well with the measured values using thermocouples installed in the steel. The results demonstrate that the method presented in this work is a promising means for high accurate rebuilding internal unsteady temperature distributions in solid structure.

Direct load monitoring of rolling bearing contacts using ultrasonic time of flight

The load applied by each rolling element on a bearing raceway controls friction, wear and service life. It is possible to infer bearing load from load cells or strain gauges on the shaft or bearing housing. However, this is not always simply and uniquely related to the real load transmitted by rolling elements directly to the raceway. Firstly, the load sharing between rolling elements in the raceway is statically indeterminate, and secondly, in a machine with non-steady loading, the load path is complex and highly transient being subject to the dynamic behaviour of the transmission system. This study describes a method to measure the load transmitted directly by a rolling element to the raceway by using the time of flight (ToF) of a reflected ultrasonic pulse. A piezoelectric sensor was permanently bonded onto the bore surface of the inner raceway of a cylindrical roller bearing. The ToF of an ultrasonic pulse from the sensor to the roller–raceway contact was measured. This ToF depends on the speed of the wave and the thickness of the raceway. The speed of an ultrasonic wave changes with the state of the stress, known as the acoustoelastic effect. The thickness of the material varies when deflection occurs as the contacting surfaces are subjected to load. In addition, the contact stiffness changes the phase of the reflected signal and in simple peak-to-peak measurement, this appears as a change in the ToF. In this work, the Hilbert transform was used to remove this contact dependent phase shift. Experiments have been performed on both a model line contact and a single row cylindrical roller bearing from the planet gear of a wind turbine epicyclic gearbox. The change in ToF under different bearing loads was recorded and used to determine the deflection of the raceway. This was then related to the bearing load using a simple elastic contact model. Measured load from the ultrasonic reflection was compared with the applied bearing load with good agreement. The technique shows promise as an effective method for load monitoring in real-world bearing applications.

Wheelchairs Embedded Control System Design for Secure Navigation with RF Signal Triangulation

In the mobile robotic systems a precise estimate of the robot pose (Cartesian [x y] position plus orientation angle ?) with the intention of the path planning optimization is essential for the correct performance, on the part of the robots, for tasks that are destined to it, especially when intention is for mobile robot autonomous navigation. This work uses a ToF (Time-of-Flight) of the RF digital signal interacting with beacons for computational triangulation in the way to provide a pose estimative at bi-dimensional indoor environment, where GPS system is out of range. It's a new technology utilization making good use of old ultrasonic ToF methodology that takes advantage of high performance multicore DSP processors to calculate ToF of the order about ns. A mobile robot platform with differential drive and nonholonomic constraints is used as base for state space, plants and measurements models that are used in the simulations and for validation the experiments. After being tested and validated in the simulator, the control system is programmed in the control board memory of the mobile robot or wheelchair. Thus, the use of material is optimized, firstly validating the entire model virtually and afterwards operating the physical implementation of the navigation system.

Determination of Density Variation and Microstructure in Reaction‐sintered SiC Ceramics Using Ultrasonic Time‐of‐Flight

Ultrasonic time‐of‐flight (TOF) is investigated as a predictor of density variation across reaction‐sintered silicon carbide (SiC) ceramics. The importance of this research is heightened by the fact that the reaction‐sintered SiC ceramic tiles being investigated are manufactured using the reaction sintering process that involves the infusion of liquid silicon into a porous ceramic preform. This can potentially lead to the formation of islands of free silicon, small closed areas of un‐sintered silicon material as well as conventional porosity. All these defects can result in local variations of density which cannot be detected by conventional bulk density measurement techniques. To study the microstructural differences, the porosity dependence of ultrasonic TOF of the reflected signals was investigated to establish a correlation between the velocity and density across the ceramic tile that aids in characterizing the material. The data suggest that for these ceramic tiles, TOF C‐scan mapping surfs as a much better indicator of sample homogeneity than the amplitude of the back wall echo. At the current time, ceramic tiles are inspected offline and this takes time and effort and is very expensive. In particular, this study contains the procedure followed to establish a quantitative method to quantify density variation across selected ceramic tile.

Mobile Robot Indoor Autonomous Navigation with Position Estimation Using RF Signal Triangulation

In the mobile robotic systems a precise estimate of the robot pose (Cartesian [x y] position plus orientation angle theta) with the intention of the path planning optimization is essential for the correct performance, on the part of the robots, for tasks that are destined to it, especially when intention is for mobile robot autonomous navigation. This work uses a ToF (Time-of-Flight) of the RF digital signal interacting with beacons for computational triangulation in the way to provide a pose estimative at bi-dimensional indoor environment, where GPS system is out of range. It’s a new technology utilization making good use of old ultrasonic ToF methodology that takes advantage of high performance multicore DSP processors to calculate ToF of the order about ns. Sensors data like odometry, compass and the result of triangulation Cartesian estimative, are fused in a Kalman filter in the way to perform optimal estimation and correct robot pose. A mobile robot platform with differential drive and nonholonomic constraints is used as base for state space, plants and measurements models that are used in the simulations and for validation the experiments.

Accurate time synchronization of ultrasonic TOF measurements in IEEE 802.15.4 based wireless sensor networks

This paper discusses the problem of accurate time synchronization of wireless sensor networks (WSNs) used in applications in which a physical phenomenon must be monitored through periodical sampling. In some applications incorrect time synchronization can significantly degrade the system precision. This is for example the case of local positioning systems (LPSs) using ultrasonic time of flight (TOF) measurements for pseudorange estimation. The nodes clock drifts and the random variations of the start time used in each measurement are the two main error sources. In this work a Time Division Multiple Access (TDMA) synchronization algorithm is presented to overcome these problems for WSN using the IEEE 802.15.4 standard. The algorithm is able to compensate for the mentioned error sources in an easy and effective way. Experimental results for an implementation of an ultrasonic pseudorange measurement system between wireless nodes show the effectiveness of the proposed algorithm.

A proposal of multi-imaging system of electrical and ultrasonic properties

In this paper, we propose a multi-imaging system which can simultaneously create both an ultrasound and electrical impedance images by using the data collected by piezoelectric ceramic transducers (PZTs) for the living body. In the proposed system, ultrasonic time of flight is not only measured by several combinations of PZTs arranged around the target and but also measured by those of front surface electrodes of PZTs. From these data, the electrical and ultrasonic properties at the same space are simultaneously reconstructed. This enables advancement of the detection ability in the target because two different images at the same space are simultaneously obtained. First of all, we established an ultrasound reflective and electrical impedance imaging system with 16 PZTs. As the experiments, we demonstrated both reconstructed images of electrical and ultrasonic properties from measurement data of electrical conductance and ultrasonic time of flight.

Feasibility of Ultrasonic Log Sorting in Manufacturing Structural Lamination from Japanese Cedar Logs

Because Japanese cedar shows lower mechanical performance, glued-laminated timber (glulam) can be a better way to utilize Japanese cedar for structural purpose. However, low yield of higher grade lami- nation from log makes it difficult to design structural glulam. This study was aimed to increase the yield of higher grade lamination and provide higher efficiency of manufacturing structural lamination by ultra- sonic log sorting technology. Logs were sorted by an existing log grading rule regulated by Korea Forest Research Institute (KFRI). It was found that the KFRI log grading rule contributed to finding better logs in viewpoint of the volumetric yield and it can reduce the number of rejected lumber by visual grading. However, it could not identify better logs to produce higher-grade products. To find an appropriate log-sorting-method for structural products, log diameter and ultrasonic time of flight (TOF) for the log were considered as factors to affect mechanical performance of resulting products. However, it was found that influence of log diameter on mechanical performance of resulting products was very small. The TOF showed a possibility to sort logs by mechanical performance of resulting products even though a co- efficient of correlation was not strong (R = 0.6). In a case study, the log selection based on the ultrasonic TOF of the log increased the yield of the outermost tension lamination (E8 or better grade, KS F 3021) from 2.6% to 12.5% and reduced LTE5 (lower than E5 grade) lamination from 43.6% to 10.3%, compared with the existing KFRI log grading rule.